A method for printing characters and designs onto a base material such as fabrics includes pigment textile printing methods.
In pigment textile printing methods, a textile printing agent consisting of a coloring pigment and a binder resin is printed on a base material, then the base material is heated, dried and cured to fix the printing agent on it.
The printing methods include a silk screen method wherein a pattern of a screen mesh extended on a screen holder is continuously printed, and a rotary screen method wherein a pattern of a cylindrical metallic screen mesh is continuously printed. As a screen printing machine used for these printing methods, there are a long hand-screen printing machine to print on lengthy materials, a running-type or belt-conveyer-type automatic screen printing machine, a rotary screen printing machine and others.
Meanwhile, as a printing machine used for printing cut fabrics and sewing products such as T shirts, there are a T-shirt textile printing table wherein a material is placed on a printing table so that it is printed by a hand screen; a rotating (turntable-type) automatic printing machine wherein stages consisting of a screen onto which a screen mesh is extended and a dryer are placed radial to the center of a turntable at its circumference, and wherein multicolor screen printing is enabled by intermittently rotating and revolving a pallet (printing table); and an elliptical multi-station screen textile printing machine wherein stages consisting of a screen onto which a screen mesh is extended, a dryer and a cooling machine are placed in an elliptical shape, and wherein multicolor screen printing is enabled by rotating and revolving a pallet (printing table).
Items related to the pigment textile printing methods include, for example, (a) a printing method on a polyurethane foam as a material to be printed, wherein a soft polyurethane resin paint as a ground coating agent is coated on the material to be printed with a coating amount of 25-100 g/m2 to form a cover of ground, which is either naturally dried or dried/solidified by heating, and one or more screen printing plates corresponding to the number of colors for characters and design to be multicolor-printed are placed on said material having said cover of ground, then plastisol inks with respective colors are printed on said material, which are then sequentially naturally dried or dried/solidified by heating (Patent document 1), (b) a fabric having a photoluminescent pattern, wherein on the surface of the dyed and finished fabric, desired characters and patterns are printed using coloring pastes having a pigment, a binder resin, metallic powder and/or glass beads as major components (Patent document 2), (c) a printed material having a suede-like surface consisting of a ground layer [2] printed on a base material[1] using an undercoating ink, a middle layer[3] formed by recoating said ground layer with a plastisol ink containing a vinyl chloride resin, and an overcoating layer[4] formed by recoating said middle layer with a plastisol ink containing a foaming agent and a vinyl chloride resin (Patent document 3).    [Patent document 1] JP, A, 10-337945    [Patent document 2] JP, A, 2004-84149    [Patent document 3] JP, A, 2006-82255
In the above examples, multicolor rotating screen printing machines are not used.
A multicolor rotating screen printing machine uses a plastisol ink consisting of a vinyl chloride resin and a plasticizer to print on base materials such as a fabric, wherein after screen printing on the base material such as a fabric, said ink is semi-gelatinized by, for example, far-infrared radiation for 6-10 s using a far-infrared dryer, and thus no tack develops on the printed surface even under heating conditions; accordingly, even if the printed surface is pressed during printing of the next screen, continuous printing is possible without blocking the back surface of the next screen.
In addition, in the case of printing on a colored fabric, after a white plastisol ink is printed on the entire design of the colored fabric as a hiding layer and is irradiation-dried using a far-infrared dryer, said plastisol ink enables wet-on-wet printing of a colored ink.
This is considered to be possible because a large amount of plasticizer is contained in the plastisol ink, the plasticizer bleeds on the printed surface to suppress the blocking of the back surface of the next screen.
Furthermore, the plastisol ink does not dry under normal temperature, preventing the clogging during continuous printing; thus, the plastisol ink is considered to be a suitable ink for multicolor rotating screen printing machines.
However, with respect to plastisol inks consisting of a vinyl chloride resin and a plasticizer, an environment-related problem has been pointed out; in addition, there are problems of defects in terms of quality of printed materials, including heavy weight of printed parts, no breathability, hardening/shrinking and cracking due to elution of the plasticizer by washing.
Regarding this environmental problem, an acrylic plastisol ink has been developed recently (Patent document 4).
However, in this developed ink, only the vinyl chloride resin is replaced with an acrylic resin, and the plasticizer is still contained; therefore, the environmental problem has not yet been solved. Moreover, preservation stability of the ink is deteriorated due to high swellability of acrylic resins to plasticizers. Furthermore, regarding the quality of textile printed materials, the defects of vinyl chloride plastisol inks such as no breathability, hardening/shrinking and cracking due to elution of the plasticizer by washing have not yet been solved.    [Patent document 4] JP, A, 07-157622
Under the above-mentioned circumstances, the development of an aqueous printing composition having superior printing characteristics, which does not cause environmental problems and which enables the use of multicolor rotating screen printing machines has been awaited.